Maintaining dies in an injection press parallel to each other

ABSTRACT

In an injection press having a mold in the form of a moveable die positioned on a moveable plate and a fixed die positioned on a fixed plate, the moveable die is moved to a compression starting position which is spaced slightly from the fixed die, the resin to be molded is injected into the mold cavity between the two dies, and the moveable die is then moved towards the fixed die to compress the thus injected resin. The compression starting position is determined by mechanical positioning means which can adjust the compression starting position. The stroke deviation for the compression can be adjusted by detecting the position of the moveable plate during the compression stroke so that the levelness of the moveable die can always be maintained during the compression stroke. Thus, the parallelism of the two dies can be stably maintained against the injection pressure.

TECHNICAL FIELD

The present invention relates to an injection press device and a formingmethod therefor, and, more particularly, to an improvement in aninjection press device and a forming method therefor capable ofsatisfactorily maintaining the parallelism of dies at the time of dieclamping work.

BACKGROUND ART

Hitherto, as a method of determining the compression stroke for clampingthe die at the time of injection press forming and injection compressionforming, there has been (1) a structure as disclosed in Japanese patentLaid-Open No. 58-167132, Japanese Patent Laid-Open No. 58-167137 and thelike in which it is determined by inserting a key between a moveableplate and an end plate or between a fixed plate and a moveable plate,and (2) a structure as disclosed in Japanese Patent Laid-Open No.60-179218, Japanese Patent Laid-Open No. 60-37297 and the like in whicha positioning cylinder is provided between the moveable plate and thefixed plate so that it is determined by the cylinder stroke.

However, according to the above-described structures, only thecompression stroke is determined and means to maintain the parallelismbetween the dies has not been described. As for the parallelism of thedies, parallelism from the compression starting point becomes criticalin injection press forming in which the compression stroke is relativelylarge with respect to that in injection compression forming. Ifsatisfactory parallelism cannot be realized, the action of the moltenresin is influenced, causing the quality of the product to becomeunsatisfactory.

Accordingly, an object of the present invention is to provide aninjection press device and a forming method therefor capable ofrealizing a satisfactory die parallelism and from which products of goodquality can thereby be obtained.

DISCLOSURE OF THE INVENTION

In order to achieve the above-described object, an injection pressdevice according to the present invention is characterized by: a fixeddie plate supporting a fixed die; a moveable die plate supporting amoveable die which is brought into contact with the fixed die and movedaway from the same to a compression start position by liquid pressuremeans; an injection mechanism for injecting molten resin into a cavityformed by joining the two dies; mechanical positioning means fastenedadjacent to the fixed die plate for the purpose of restricting thereturn movement of the moveable die plate at a compression startingposition during a stroke of the moveable die plate; an adjuster fastenedadjacent to the fixed die plate for adjusting the height of themechanical positioning means and adjusting the parallelism of themoveable die plate; compression liquid pressure means, providedindependently from the liquid pressure means, for the purpose of movingthe moveable die plate from the compression start position towards thefixed die plate; a servo valve for controlling the quantity of operatingfluid to be supplied to the compression liquid pressure means; aposition sensor for detecting the position of the moveable die plate;and control means for adjusting the degree of opening of the servo valveconnected to the compression liquid pressure means in accordance withthe result of detection performed by the position sensor.

According to the above-described structure, during the stroke of themoveable die with respect to the fixed die, the moveable die is firstmoved to a required opening degree by a lift cylinder or the like, andit becomes the compression starting position. At this position, themechanical positioning means is operated and the moveable die plate ismaintained at the compression starting position. After theabove-described maintaining operation performed by the mechanicalpositioning means, the adjuster is operated so that the height of themechanical positioning means can be adjusted. Since the mechanicalpositioning means influences the parallelism of the moveable die plate,the moveable die plate can be finely adjusted by properly operating theadjuster. Thus, the rearward movement or the like of the moveable dieplate due to the injection pressure can be prevented, and theparallelism between the two dies can be maintained. Furthermore, thecompression stroke is conducted with detecting the levelness of the dieplate by the position sensor with the lift frame of the moveable dieplate positioned at the compression starting position by the mechanicalpositioning means. Thus, the levelness of the die can be maintained byadjusting the flow to be supplied to the compression fluid pressuremeans. Therefore, the action of molten resin in the cavity can be alwaysstabilized so that stabilized quality products can be obtained.

In one embodiment, the mechanical positioning means may compriseprojection and recess fitting portion disposed between the fixed dieplate and the moveable die plate and clamping means for clamping thefitting portion for maintaining the position. It may comprise a liftguide rod for guiding the stroke of the moveable die plate andscrew-fixed to the fixed die plate and means for rotating the lift guiderod, and the mechanical positioning means is secured to the lift guiderod.

As a result, the mechanical positioning can be conducted whilemaintaining the positional relationship between the two dies and whilecausing the guide function of the moveable die plate having long stroketo be conducted. Since the parallelism is adjusted by vertically movingthe lift guide rod to which the moveable die plate is integrally formed,the adjustment work can be completed quickly.

In another case, the mechanical positioning means may comprisecompression liquid pressure means moveably fastened to the fixed dieplate and capable of moving to the backside of the moveable die plate.The adjuster may be provided with a screw rod fastened to the fixed dieplate and connected to a frame having a supporting point of movement ofthe compression liquid pressure means.

As a result, the mechanical positioning means and the adjuster can beconcentrated in the fixed die plate portion so that the size of thefitting structure can be reduced.

When the compression fluid pressure means is interposed between the liftframe and the moveable die plate so that only the compression process isperformed by the compression fluid pressure means, the flow control tothe compression fluid pressure means can be assuredly conducted. As aresult, the control of the levelness of the die can be satisfactorilyconducted.

One embodiment of the invention is a specific combination of theabove-described structures, that is, it comprises a fixed die platesupporting a fixed die; a lift guide rod erected from the fixed dieplate; a moveable die plate supporting a moveable die which is broughtinto contact with the fixed die and moved away from the same by a liquidpressure means to a compression start position under the guidance of thelift guide rod; an injection mechanism for injecting molten resin into acavity formed by joining the two dies; mechanical positioning meansfastened adjacent to the fixed die plate for the purpose of restrictingthe return movement of the moveable die plate at a compression startingposition during a stroke of the moveable die plate; an adjuster foradjusting the height of the mechanical positioning means and adjustingthe parallelism of the moveable die plate; compression liquid pressuremeans, provided independently from the liquid pressure means, for thepurpose of moving the moveable die plate from the compression startposition towards the fixed die plate; a servo valve for controlling thequantity of operating fluid to be supplied to the compression liquidpressure means; a position sensor for detecting the position of themoveable die plate; and control means for adjusting the degree ofopening of the servo valve connected to the compression liquid pressuremeans in accordance with the result of detection performed by theposition sensor, wherein the mechanical positioning means comprises asleeve provided for the moveable die plate and arranged to be penetratedby a lift guide rod, a catcher case secured to the lift guide rod andinto which the sleeve is fitted and clamping means fastened to thecatcher case and for abutting the sleeve, and the adjuster comprises alift guide rod screw-fixed to the fixed die plate and means for rotatingthe lift guide rod.

In another embodiment, a structure may be employed which comprises: afixed die plate supporting a fixed die; a frame integrally formed withthe fixed die plate; a lift guide rod erected from the fixed die plate;a moveable die plate supporting a moveable die which is brought intocontact with the fixed die and moved away from the same to a compressionstart position by liquid pressure means fastened to the frame; aninjection mechanism for injecting molten resin into a cavity formed byjoining the two dies; mechanical positioning means fastened adjacent tothe fixed die plate for the purpose of restricting the return movementof the moveable die plate at a compression starting position during astroke of the moveable die plate; an adjuster for adjusting the heightof the mechanical positioning means and adjusting the parallelism of themoveable die plate; compression liquid pressure means, providedindependently from the liquid pressure means, for the purpose of movingthe moveable die plate from the compression start position towards thefixed die plate; a servo valve for controlling the quantity of operatingfluid to be supplied to the compression liquid pressure means; aposition sensor for detecting the position of the moveable die plate;and control means for adjusting the degree of opening of the servo valveconnected to the compression liquid pressure means in accordance withthe result of detection performed by the position sensor, wherein themechanical positioning means comprises a compression cylinder moveablyfastened to the moveable die plate and capable of moving to the backside of the moveable die plate and the adjuster is provided with a screwrod penetrating the fixed die plate and connected to the mechanicalpositioning means so that the mechanical positioning means can bevertically moved.

According to any of the structures described above, the stroke of thedie is correctly defined to the compression stroke starting position.Furthermore, the parallelism of the dies at the compression start can besecured. Therefore, the action of the molten resin in the die can bealways constant. Therefore, products of stable quality can be obtained.Furthermore, since the positioning function is mechanically conducted,the positioning work can be extremely stably conducted.

Furthermore, according to the present invention, there is provided aninjection press forming method for injecting and supplying molten resinto a cavity formed by a die and performing a forming by compressing andcooling, the injection press forming method being characterized by:utilizing a sensor to detect the position of a moveable die plate withrespect to a fixed die plate; controlling the flow and the pressurelevel of operating fluid to a plurality of compression cylinders inaccordance with the result of the detection; and performing acompression process while maintaining the parallelism of the die platewith respect to the fixed die plate when injection is performed afterthe moveable die plate has been positioned to a compression startingposition by mechanical positioning means and the plurality ofcompression cylinders disposed between a lift frame and the moveable dieplate are operated so as to move and perform the compression with thedie closed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front elevational view of an injection press deviceaccording to a first embodiment of the present invention;

FIG. 2 is a circuit diagram for the injection press device according tothe first embodiment of the present invention;

FIGS. 3 to 9 illustrate the operation of the first embodiment of thepresent invention;

FIG. 10 is a graph which illustrates the stroke position andmanufacturing process of the device according to the first embodiment ofthe present invention;

FIG. 11 is a front elevational view which illustrates the injectionpress device according to a second embodiment of the present invention;and

FIGS. 12 to 15 illustrate the operation of the second embodiment of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of injection press device according to the present inventionwill be described in detail with reference to the drawings. FIGS. 1 to10 illustrate a first embodiment of the present invention.

Referring to FIG. 1, reference numeral 1 represents an injection presscomprising a movable plate 30 and a fixed plate 40. The fixed plate 40comprises a die plate 10 to which a lower die 13 can be fastened and aframe 11 for supporting the die plate 10. The die plate 10 has fourerected lift guide rods 2. The moveable plate 30 comprises a lift frame3 and an upper die plate 5. The lift frame 3 is positioned above thefixed die plate 10, with the four lift guide rods 2 extending throughthe lift frame 3. The lift frame 3 is capable of being moved vertically.The upper die plate 5 is supported from the lift frame 3 by fourcompression cylinders 4 which are included in the lift frame 3. An upperdie 12 is secured to the upper die plate 5 in such a manner that theupper die 12 confronts the lower die 13 of the fixed plate 40. On eachof the four lift guide rods 2 a catcher case 6 is provided, with eachcatcher case 5 including a lock cylinder 7. Each catcher case 6 has afastening recessed portion 6A at the portion through which therespective lift guide rod 2 passes. The lift frame 3 is provided withfour insertion sleeves 3A, with each insertion sleeve 3A beingpositioned about a respective lift guide rod 2 so as to fit within thefastening recessed portion 6A of the respective catcher case 6. In eachcatcher case 6, the lock cylinders 7 is able to project into thefastening recessed portion 6A so that the lock cylinder abuts againstthe outer surface of the inserted sleeve 3A. As a result, the insertionsleeve 3A is mechanically clamped and fixed when the lock cylinder 7 isextended into the fastening recessed portion 6A. Four lift cylinders 8ar provided for lifting the lift frame 3, which each lift cylinder 8being integrally fastened to a respective catcher case 6. As a result,the lift frame 3 can be lifted by the application of hydraulic power tothe four lift cylinders 8.

Each of the lift guide rods 2 is fixed to the lower die plate 10 with ascrew. Therefore, the upper die plate 5 can be vertically moved wheneverthe lift guide rods 2 rotate, and the catcher cases 6 integrallyfastened to the lift guide rods 2 are simultaneously and verticallymoved. Thus, the mechanical fixing devices 50, each consisting of acatcher case 6, a lock cylinder 7, a lift cylinder 8, and a lift guiderod 2, can be individually vertically adjusted. The height can beadjusted by individually rotating the lift guide rods 2 by means ofheight adjusters 9 disposed at the upper end portions of the lift guiderods 2.

An upper die 12 is secured to the upper die plate 5, while positionsensors 14 for detecting the position of the upper die 12 relative tothe lower die 13 are secured to the die plate 10.

FIG. 2 is a circuit diagram of one of the movement control devices 60.In each motion control device 60, the compression cylinder 4, the lockcylinder 7 and the lift cylinder 8 are operated by receiving hydraulicpressure supplied from the pump 15 via a servo valve 16a for controllingthe flow, a relief valve 16b for controlling the hydraulic pressure, anelectromagnetic valve 16c, a pilot check valve 16d, an electromagneticvalve 16e, a cartridge valve 16f and a pressure reducing valve 16g. Thecircuit for the compression cylinder 4 adjusts the flow by its servo16a, capable of controlling the flow, in response to a signal suppliedfrom a control portion 17, the signal corresponding to the positiondetected by the position sensor 14. As a result of the adjustment theupper die 12 moves vertically and in parallel. Each of the movementcontrol device circuits for moving the upper die 12 in parallelcomprises a position sensor 14, a servo valve 16a, a control portion 17and a compression cylinder 4. Although the above-described circuits areoperated by a single pump, they may be operated independently.

The operation of the structure will now be described. First, thedetermination of the stroke at the time of the injection press formingwill now be described with reference to FIGS. 3 to 6. The lift frame 3is positioned at the lowermost point (each lift cylinder 8 is positionedat its shortest stroke end) and each compression cylinder 4 is alsopositioned at its shortest stroke end (as shown in FIG. 3). In thisstate, the lift frame 3 is mechanically locked to the catcher cases 6 bythe mechanical fixing devices 50 by using the lock cylinders 7. Then,hydraulic pressure is supplied to a port 8b of each left cylinder 8 soas to eliminate the backlash, and then the upper die 12 and the lowerdie 13 are brought into close contact with each other by the heightadjusters 9 (see FIG. 4). At this time, since the height adjusters 9 canindividually adjust the height of each of the four lift guide rods 2,the above-described close contact can be realized. Starting from thethus realized state, the lift frame 3 is moved upwardly by the heightadjusters 9 by a necessary compression stroke (see FIG. 5). At thistime, since the height of each of the lift guide rods 2 can beindividually adjusted by the height adjusters 9, the initial parallelismcan be maintained. Furthermore, in this state, the dies 12, 13 arebrought into close contact with each other by the compression cylinders4, the thus realized state being arranged to be the final position inthe process of condition determination.

Then, the forming operation is started.

In the initial stage of the forming operation, as shown in FIG. 7, thelock cylinders 7 are released, and the compression cylinders 4 arepositioned at their shortest stroke with hydraulic pressure beingsupplied to the port 8b of each lift cylinder 8 so that the lift frame 3is moved upwardly. Then, as shown in FIG. 8, each lift cylinder 8 ispositioned a its shortest stroke at the time of closing operation, whilethe lift frame 3 is locked by the lock cylinders 7, and hydraulicpressure is supplied to the port 8b of each lift cylinder 8 so as toeliminate the backlash at the time of the compression positioning. Asshown in FIG. 9, at the time of the forming compression, the upper die12 is lowered by the compression cylinders 4 so that resin enclosed inthe die is press-formed. At this time, the position of each of the fourcorners of the upper die plate 5 is detected by the position sensors 14disposed at the four corners of the die plate 10. The position and thespeed of each corner of the upper die plate 5 are calculated by therespective control portion shown in FIG. 2. As a result, the die 12 ismaintained parallel to die 13 while die 12 is moved towards die 13 bythe movement control devices 60 which adjust the position and the speedof the compression cylinders 4 so as to maintain the die 12 in parallelwith die 13 by adjusting the flow to each compression cylinder 4 throughits respective flow control servo valve 16a. An example of theabove-described sequential operations is shown in FIG. 10. Referring toFIG. 10, the axis of ordinate shows the position of each of the devices:the height adjusters 9, the lift cylinders 8, the degree of opening ofthe die, or the like, while the axis of abscissa shows the conditionsafter the die has been changed and the operations at the time of theforming work. Although the backlash is eliminated in the operationaccording to the above-described example by locking the lift frame 3 bythe lock cylinders 7 and supplying hydraulic pressure to the ports 8b, acylinder 101 (see FIG. 2) for eliminating the backlash may be providedadditionally. Although the movement of the upper die plate 5 is detectedat the time of the parallel movement of the upper die 12, it may bedetected by a rod or the like of the compression cylinders 4.

FIGS. 11 to 15 illustrates a second embodiment of the present invention.Referring to FIG. 11, a lift cylinder 24 for receiving hydraulicpressure from a pump (omitted from illustration) and sliding a slide 23is secured to a frame 22 of an injection press forming device 21. Anupper die 25 is fastened to the slide 23, while a lower die 27 isfastened to a die plate 26. An injection port 28 is formed in the lowerdie 27 so that molten resin from an injection mechanism (omitted fromillustration) disposed below a bolster can be injected, through theinjection port 28 into a cavity 29 formed in the dies 25, 27. The slide23 is mechanically fixed by the mechanical fixing devices 50 at aposition at which the distance between the two dies 25, 27 becomes apredetermined distance. The mechanical fixing devices 50 comprisecompression cylinders 31 for compressing resin injected into andenclosed in the cavity 29, links 32 for supporting the compressioncylinders 31, lock cylinders 33 for tilting the links 32, four heightadjusters 37 for securing links 32 and the lock cylinders 33 to cylinderframes 34 with pins 35 and 36 and moving the cylinder frames 34 inaccordance with the thickness of the die and a predetermined distancebetween the two dies, and rods 38.

The operation will now be described. The determination of thecompression stroke at the time of injection press forming will now bedescribed with reference to FIGS. 12 to 15. The slide 23 is lowered bythe lift cylinder 24 so that the upper die 25 and the lower die 27 arebrought into close contact with each other. With the compressioncylinders 31 maintained at their shortest stroke state, each mechanicalfixing device 50 for operating the lock cylinder 33 which tilts the link32 of the mechanical fixing device 50 is moved to a position shown inFIG. 12, that is, a position above the slide 23. Since the heightadjusters are, in this state, respectively adjusted so as to make thedistance between an upper surface 23a of the slide 23 and a lowersurface 31a of each compression cylinder 31 a forming compressiondistance (ΔL), the initial parallelism can be maintained (see FIG. 12).In this state, pressure may be applied to the compression cylinders 31and the lock cylinders 33 so as to eliminate the backlash.

Then, the forming operation is started.

In the initial stage, as shown in FIG. 13, each lock cylinder 33 iscontracted and the link 32 of the respective mechanical fixing device 50is tilted. Furthermore, the lift cylinder 24 is contracted so as toraise and retain the slide 23. Then, as shown in FIG. 14, the slide 23is lowered by the lift cylinder 24 at the time of closing the dies insuch a manner that the upper surface 23a of the slide 23 is lower (Sa)than the forming compression starting point (Sc). After the moving, witheach compression cylinder 31 positioned at its shortest stroke end, eachlock cylinder 33 for tilting the link 32 of the respective mechanicalfixing device 50 is operated by hydraulic pressure supplied from a pump(omitted from illustration) so that the respective mechanical fixingdevice 50 is tilted to a position shown in FIG. 14, that is, a positionabove the slide 23. Then, the lift cylinder 24 is contracted so that alower surface 31a of each compression cylinder 31 and the upper surface23a of the slide 23 are brought into contact with each other (asdesignated by a broken line). As shown in FIG. 15, the upper die 25 islowered in parallel so that resin in the die is compressed and formed.At this time, the position of the slide 23 is detected by the positionsensors 14 of the movement control devices 60 disposed at four cornersof the die plate 26 (omitted from illustration) similarly to theabove-described first embodiment. The speed is calculated by the controlportions 17 so that the position and the each of the compressioncylinders 31 are adjusted so as to maintain the two dies parallel byadjusting the flow by the respective servo valve 16a.

Although the compression stroke is determined by bringing the upper andthe lower dies into contact with each other according to theabove-described embodiment, the degree of change of the initial stagemay be maintained by first individually adjusting the height adjusters37 in the case where the size has been previously known.

Industrial Applicability

The injection press device and the method therefor according to thepresent invention can be applied to molding devices of a type whichforms resin by injection and compression.

What is claimed is:
 1. An injection press forming method for injectingand supplying molten resin to a cavity formed by a fixed die positioinedon a fixed die plate and a movable die positioned on a movable dieplate, and performing a forming of the injected molten resin bycompressing and cooling, said injection press forming method beingcharacterized by:utilizing mechanical positioning means to position saidmoveable die plate, having said movable die associated therewith, to acompression starting position whereat injection of the molten resin intosaid cavity is performed; detecting the position of said moveable dieplate with respect to said fixed die plate; controlling the flow and thepressure level of operating fluid to a plurality of compressioncylinders, disposed between a lift frame and said moveable die plate, inaccordance with the result of the detection of the position of themoveable die plate in order to compress the injected molten resin whilemaintaining the parallelism of said moveable die plate with respect tosaid fixed die plate during the compression of the injected moltenresin.
 2. An injection press device adapted to utilize an injectionmechanism to inject molten resin into a cavity, formed by joining amoveable die and a fixed die, and to effect injection press forming ofthe injected molten resin, said injection press device beingcharacterized by:a fixed die plate adapted to support said fixed die; amoveable die plate adapted to support said moveable die; die movingmeans adapted to reciprocally move said moveable die plate to bring saidmovable die supported thereby towards said fixed die supported by saidfixed die plate and then to move the supported moveable die away fromthe supported fixed die to a compression starting position; said fixeddie plate being adapted to receive said injection mechanism forinjecting molten resin into the cavity formed by joining said supportedmoveable die and said supported fixed die; mechanical positioning meansfastened adjacent to said fixed die plate and adapted to restrict themovement of said moveable die plate away from said fixed die plate atsaid compression starting position; adjusting means fastened adjacent tosaid fixed die plate and adapted to adjust the height of said mechanicalpositioning means with respect to said fixed die plate and for adjustingthe parallelism of said moveable die plate to said fixed die plate;position sensing means for detecting the position of said moveable dieplate relative to said fixed die plate and for producing a controlsignal responsive to such detection; first compression means adapted tomove said moveable die plate from said compression starting positiontoward said fixed die plate to compress molten resin which has beeninjected into said cavity; and control means for controlling said firstcompression means in accordance with the control signal produced by saidposition sensing means.
 3. An injection press device in accordance withclaim 2 wherein said die moving means is operated by the pressure of anoperating fluid, and wherein said first compression means is operated bythe pressure of an operating fluid.
 4. An injection press device inaccordance with claim 3 further comprising first supply means forsupplying operating liquid to said die moving means, and second supplymeans for supplying operating liquid to said first compression means,said second supply means being operable independently from said firstsupply means.
 5. An injection press device in accordance with claim 2wherein said adjusting means comprises at least two rods, and means foradjusting the vertical position of each such rod with respect to saidfixed die plate, said mechanical positioning means being secured to saidat least two rods.
 6. An injection press device in accordance with claim2 wherein said die moving means is adapted to reciprocally move saidmoveable die plate to bring the supported moveable die into contact withthe supported fixed die and then to move the supported moveable die awayfrom the supported fixed die to said compression starting position. 7.An injection press device in accordance with claim 2 further comprisingan injection mechanism for injecting molten resin into the cavity formedby joining the supported moveable die and the supported fixed die.
 8. Aninjection press device in accordance with claim 2 wherein saidmechanical positioning means comprises a projection and recess fittingportion disposed between said fixed die plate and said moveable dieplate, and clamping means for clamping said projection and recessfitting portion in order to maintain said moveable die plate at saidcompression starting position.
 9. An injection press device inaccordance with claim 8 wherein said adjusting means comprises at leastone lift guide rod for guiding the stroke of said moveable die plate,and means for adjusting the vertical position of each such lift guiderod with respect to said fixed die plate, said mechanical positioningmeans being secured to said at least one lift guide rod.
 10. Aninjection press device in accordance with claim 9 wherein said firstcompression means adapted to move said moveable die plate from saidcompression starting position toward said fixed die plate comprises alift frame for supporting said moveable die plate, and a plurality offluid operated compression cylinders positioned between said lift frameand said moveable die plate.
 11. An injection press device in accordancewith claim 10 wherein said die moving means accomplishes the reciprocalmovement of said moveable die plate by reciprocally moving said liftframe.
 12. An injection press device in accordance with claim 10 whereinsaid control means controls the flow and the pressure level of operatingfluid to said plurality of compression cylinders in accordance with thecontrol signal produced by said position sensing means in order tocompress the injected molten resin while maintaining the parallelism ofsaid moveable die plate with respect to said fixed die plate during thecompression of said injected molten resin.
 13. An injection press devicein accordance with claim 2 wherein said first compression means adaptedto move said moveable die plate from said compression starting positiontoward said fixed die plate comprises a lift frame for supporting saidmoveable die plate, and a plurality of fluid operated compressioncylinders positioned between said lift frame and said moveable dieplate.
 14. An injection press device in accordance with claim 13 whereinsaid die moving means accomplishes the reciprocal movement of saidmoveable die plate by reciprocally moving said lift frame.
 15. Aninjection press device in accordance with claim 2 wherein said adjustingmeans comprises at least one lift guide rod for guiding the stroke ofsaid moveable die plate, and means for adjusting the vertical positionof each such lift guide rod with respect to said fixed die plate, saidmechanical positioning means being secured to said at least one liftguide rod.
 16. An injection press device in accordance with claim 2wherein said mechanical positioning means comprises second compressionmeans moveably secured to said fixed die plate and adapted to move tothe backside of said moveable die plate which is away from said fixeddie plate.
 17. An injection press device in accordance with claim 16wherein said adjusting means comprises a rod associated with said fixeddie plate and connected to a support frame having a supporting point ofmovement of said second compression means, and a height adjuster formoving said support frame.
 18. An injection press device in accordancewith claim 2 wherein said first compression means comprises a pluralityof compression cylinders; and wherein said control means controls theflow and the pressure level of operating fluid to said plurality ofcompression cylinders in accordance with the control signal produced bysaid position sensing means in order to compress the injected moltenresin while maintaining the parallelism of said moveable die plate withrespect to said fixed die plate during the compression of said injectedmolten resin.
 19. An injection press device characterized by:a fixed dieplate supporting a fixed die; a lift guide rod erected from said fixeddie plate; a moveable die plate supporting a moveable die which isbrought into contact with said fixed die and moved away from said fixeddie by a liquid pressure means as guided by said lift guide rod; aninjection mechanism for injecting molten resin into a cavity formed byjoining said fixed die and said moveable die; mechanical positioningmeans fastened adjacent to said fixed die plate for the purpose ofrestricting the return movement of said moveable die plate at acompression starting position during a stroke of said moveable dieplate; an adjuster for adjusting the height of said mechanicalpositioning means and adjusting the parallelism of said moveable dieplate to said fixed die plate; compression liquid pressure meansprovided independently from said liquid pressure means, said liquidpressure means being for the purpose of moving said moveable die plateto said compression starting position, said compression liquid pressuremeans being for the purpose of moving said moveable die plate from saidcompression starting position towards said fixed die plate to compressmolten material which has been injected into said cavity; a servo valvefor controlling the quantity of operating fluid to be supplied to saidcompression liquid pressure means; a position sensor for detecting theposition of said moveable die plate; and control means for adjusting thedegree of opening of said servo valve connected to said compressionliquid pressure means in accordance with the result of detectionperformed by said position sensor; wherein said mechanical positioningmeans comprises a sleeve arranged to be penetrated by said lift guiderod, a catcher case secured to said lift guide rod and into which saidsleeve is fitted, and clamping means fastened to said catcher case andfor abutting said sleeve; wherein said lift guide rod is screw-fixed tosaid fixed die plate; and wherein said adjuster comprises means forrotating said lift guide rod.
 20. An injection press device adapted toinjection press form molten resin in a cavity formed by joining amoveable die and a fixed die, said injection press device beingcharacterized by:a fixed die plate adapted to support said fixed die; aframe integrally formed with said fixed die plate; a lift guide roderected from said fixed die plate; a liquid pressure means fastened tosaid frame; a moveable die plate adapted to support said moveable die assaid movable die is brought into contact with said fixed die and movedaway from the same to a compression starting position by said liquidpressure means, said moveable die plate having a back side remote fromsaid fixed die plate; an injection mechanism adapted to inject moltenresin into the cavity formed by joining the moveable die and the fixeddie; mechanical positioning means fastened adjacent to said fixed dieplate for the purpose of restricting the return movement of saidmoveable die plate at said compression starting position during a strokeof said moveable die plate; an adjuster for adjusting the height of saidmechanical positioning means and adjusting the parallelism of saidmoveable die plate relative to said fixed die plate; compression liquidpressure means provided independently from said liquid pressure means,said compression liquid pressure means being for the purpose of movingsaid moveable die plate from said compression starting position towardssaid fixed die plate; a servo valve for controlling the quantity ofoperating fluid to be supplied to said compression liquid pressuremeans; a position sensor for detecting the position of said moveable dieplate; and control means for adjusting the degree of opening of saidservo valve connected to said compression liquid pressure means inaccordance with the result of detection performed by said positionsensor; wherein said mechanical positioning means comprises at least onecompression cylinder moveably fastened to said fixed die plate andcapable of moving to said back side of said moveable die plate; andwherein said adjuster is provided with a screw rod penetrating saidfixed die plate and connected to said mechanical positioning means sothat said mechanical positioning means can be vertically moved.